My sister's dog has many food allergies and I was looking for treats that were free of all the things she is allergic to. The sweet potato treats in the feed store were so expensive but the dogs loved them. So I have made yam or sweet potato treats many times. I have never followed a recipe for them. I just wash then slice the sweet potatoes or yams about 1/8 of an inch and dry them in the oven for a 2 or 3 hours at about 250 . I turn them one or 2 times to make sure they dry all the way. I test to see if they are dry by taking one out of the oven...let it cool then see if it bends. If it bends it is not dry. It should crack. If you are lucky enough to have a convection oven they dry in about half the time. They have never turned out like a chew but they are a good alternative to dog cookies. I store them in a cookie jar. I will have to say that when I first started making them I had the oven going all the time and my electric bill went up so now I only do them once in a while.